GLOBAL MAP OF MARS' TERRAIN SHOWS WHAT'S UP, WHAT'S DOWN

Members of NASA's Mars Global Surveyor science team will
unveil the first global three-dimensional map of the surface
of Mars at a press briefing on Thursday, May 27.

The topographical map gives scientists their first
detailed understanding of the relative heights of various
geologic features on the red planet, including regions that
shaped the flow of water early in Mars' history and what may
be the largest impact basin in the Solar System.

The Space Science Update will be held at 2 p.m. EDT in
the James E. Webb Auditorium at NASA Headquarters, 300 E St.
SW, Washington, DC.

The map was produced by the Mars Orbiter Laser Altimeter
(MOLA) instrument aboard Global Surveyor, which fires short
pulses of infrared light at the Martian surface and measures
the time it takes for the reflected light to return. Given
the known orbit of Global Surveyor, the resulting times allow
scientists to infer the height of the terrain below with
great accuracy.

Briefing presenters will include:

Moderator Dr. John Grant, Mars Global Surveyor program
scientist in the Office of Space Science at NASA
Headquarters.

Dr. Maria Zuber, co-investigator for the MOLA
instrument from the Massachusetts Institute of Technology,
Cambridge, MA, and NASA Goddard.

Dr. Jim Zimbelman, planetary geologist at the Center
for Earth and Planetary Studies at the Smithsonian
Institution's National Air and Space Museum, Washington, DC.

Mars Global Surveyor carries five science instruments
designed to generate a complete global portrait of Mars and
its seasonal changes during a full Martian year, the
equivalent of two Earth years. It is the first mission in a
long-term program of Mars exploration known as the Mars
Surveyor Program, which is managed by NASA's Jet Propulsion
Laboratory (JPL), Pasadena, CA, for the Office of Space
Science at NASA Headquarters. JPL's industrial partner is
Lockheed Martin Astronautics, Denver, CO, which developed and
operates the spacecraft. JPL is a division of the California
Institute of Technology.

The briefing will be carried live on NASA Television,
which is available on transponder 9C of the GE-2 satellite at
85 degrees West longitude, vertical polarization, frequency
3880 MHz, audio of 6.8 MHz. Two-way question-and-answer
capability will be available for news media at participating
NASA centers.